It could give you legal protections from discrimination.
If you're in the USA it's a toss up between the power of employers to fire at will and the notably influential ADA.
So you'd be taking a risk by declaring it to an employer you didn't trust anyway.
In other countries you can get government support etc with your therapy (and other things).
Plus knowing what kind of autism you have can help direct your care and coping strategies, which could greatly improve your quality of life